Endoscopic devices



Jan. 26, 1960 E. E. SHELDON ENDOSCOPIC DEVICES 4 Sheets-Sheet 1 Filed Feb. 14, 1957 ED WARD EMA/\ l/EL SHELDON INVENTOR.

ATTORNEY 4 Sheets-Sheet 3 BY X/A/MMW,

Array/v6) Jan. 26, 1960 Filed Feb. 14, 1957 R M 6 a m L llllm FM 1 5 I a, z a 2 l W a A WW PM 2 3 U W flJ m a A 0/ r .Hv... M 5 Z a a I E F W Z m m. M a M" M v, y a ,2 I z 5 M ,2. M w: w\\w Jan.- 26, 1960 E. E. SHELDON ENDOSCOPIC DEVICES Filed Feb. 14, 1957 4 Sheets-Sheet 4 [DWA/PD EMANUEL Susana/v BYff ATTORNE' Y United States Patent ENDOSCOPIC DEVICES Edward Emanuel Sheldon, New York, NY.

Application February 14, 1957, Serial No. 640,281

8 Claims. (Cl. 1786.8)

' This invention relates to a novel endoscopic instrument, i.e. instrument for examination of the internal organs, parts or passages-of the body which are inaccessible to examiner.

The present endoscopic devices consist of straight tubes which are either hollow or are provided with lenses or prisms. Due to inability of light to see around the corners, the present endoscopes have to be absolutely straight and rigid so that the eye of the examiner and the examined part of the patients body are in one straight line. The endoscopes using optical lenses or prisms do not improve this situation as the shape and the size of the ex amined organs is so variable that the position of the curves and angles of the organs is absolutely unpredictable and therefore the lenses or prisms cannot be positioned to anticipate these multiple deviations of the axis of the examined organ from the straight line.

The purpose of my invention is to provide a method and device for visual examination of the internal organs regardless of their size and shape and of the angle of their curvatures which was impossible until now and represents therefore an important process in medical diagnosis.

Another purpose of this invention is to provide means for introduction of the endoscopic instrument into a patients body under constant visual control which is the most important factor in the safety ofperformance of endoscopic examination.

Another purpose of my invention is to enable simultaneous observation of said inaccessible parts by many examiners, situated in close or remote locations, which was not possible until now.

Another objective of this invention is to change, decrease or amplify the contrast of the image of the examined part.

The objectives of my invention were realized by a novel device which is flexible to allow its introduction into the examined part regardless of its curvatures or angulations and which after its introduction into the examined part will produce a light image of said part. Video signals are reconverted in receivers outside of the examined part into visible images for inspection or recording. My intrascopic device can produce black and white images, as well as multi-color images, showing faithfully or arbitrarily the colors of the examined part.

In particular this novel device makes use'of a televi-' sion pick-up tube consisting of two separate independent elements which can be introduced separately into the examined part and which after introduction work in coop-- eration as a television camera. As each of these two separate elements is smaller in size than any conventional television camera can be made, this novel television cam era can be introduced into locations which, because of small size or tortuous shape of passages leading to them, were inaccessible to the most miniaturized television cam eras known in the art. e

Another marked improvement in my novel television camera is elimination of-magnetic deflecting coils which are bulky and occupy so much space that even a small capable of producing images of a good definition 2,922,844 Patented Jan. 26,

2 television tube using them cannot be introduced into narrow passages. The use of conventional electrostatic deflecting system resultsinto a marked distortion of images especially in pick-up tubes using the slow scanning electron beam. These drawbacks are eliminated in applicants intrascope and therefore in spite of its very small size it is and contrast. 1 i

In the drawings: Fig. 1 represents a partially sectioned view of the novel instrument for inspection of inaccessible parts; i Fig. 1a shows a modification of the intrascope; Fig. 1b shows the intrascope in combination with the pushing guide for introduction of component parts of the television camera into the intrascope; Fig. 2 shows the intrascope provided with a modification of the television camera;

Figs. 2a, 2b and 20 represent modifications of the television camera; j

Figs. 2d and 2e represent a cross-sectional perspective view of supporting element for the composite target in the television camera; v

Fig. 3 shows a modification of the intrascope having an optical system;

Figs. 4, 4a and 4b show simplified cameras for the intrascope; f

Fig. 5 shows an intrascope without illuminating source; Fig. 5a is a simplified form of intrascope shown in Fig. 5;

Fig. 6 represents an intrascope for producing color images; I

Fig. 6a represents color disc; Fig. 7 represents a modification of the intrascope for color images; i

Fig; 7a represents for color images;

Fig. 8 represents an intrascope sensitive to invisible images; and' p g Fig. 8a represents a modification of an intrascope sens? tive to invisible images. i

Fig. 8b represents a modification of pick-up tube. This new device which may be called the'intra'scope 1 is shown in Fig. l. The handle 2 is ahollow tube of 'diameter corresponding to the examined part.* The handle may be rigid or semi-flexible or completely flexible according to the part to be examined. At the end of the handle begins the flexible pant 2a of the intrascope which also has width and length suitable for the size of the examined part. In case the intrascope is used for examination of fragile parts, the part 2a must be very flexible and pliable in order to avoid damage to the wall of theexa simplified form of an intrascojpe amined part. The basic feature of the material for the flexible part of the intrascope is therefore thatit must be easily bent and molded by the walls of the passages in which it is being introduced. Such material may be rub ber 26 or a suitable plastic, of the type used by Davol Rubber Company of Providence, Rhode Island. In case the intrascope is used for investigation of sturdy parts or of machinery, the part 2a may be obviously more rigid. The flexible part 2a of the intrascope maybe in such a case made of the. stainless steel spiral sheet designed not only for durability but also to maintain the'proper degree of flexibility andelasticity. The metal spiral is tapered to insure its uniform bending. The intrascope may be covered with an outer tubing 26a such'as of neoprene. This prevents dust particles and moisture from affecting the optical and pick-up system located inside of the intrascope. At the end of the flexible part there is a semi-flexible tip 3 which may be screwed on the flexible part and can be easily removed giving thereby access to the inner structures of the intrascope. The tip consists of a rubber conical finger and serves to facilitate attachment of the box is externally to the examined part.

the gliding of the intrascope within the examined part. In order to facilitate the introduction of the intrascope into parts which have no curves, my device can be made semi-rigid by inserting into it a semi-rigid stilet. In case the intrascope is used as a probe for insertion into a solid object, the tip 3 should be preferably rigid and sharply pointed to be able to pierce the examined object.

In some cases the examined part has to be distended by air or fluid insufilation prior to the examination. A special air pump attachment 44 and a channel 44a in the intrascope in provided for this purpose. The channel 44a may also serve to evacuate contents of the examined part before examination to improve visibility. The knob 45 on the proximal end of the intrascope serves to indicate to the examiner the position of windows 12 and 18 of the intrascope. In some cases the layer 26 or 26a should be of a highly dielectric material to prevent any short circuits. I

In the distal end of the flexible part of the intrascope I i there is a housing box 5 containing the illumination system 7. The box 5 may also be attached to the inner walls of the intrascope by means of the brackets or may be held by springs. It is obvious that there are many means for 5 which are well known in the art. All walls of the housing box 5 except the one facing the television pick-up tube 16 are provided with windows for transmission of the light from the illuminating system 7. These windows are correlated with the windows 12 in the flexible part of the intrascope which transmit the light from the illuminating system to the examined part. In some cases the windows 12 may be made to extend over the circumference of the intrascope. In some cases the window to transmit illumination from the light source to the examined part may also be provided in the distal end of the intrascope instead of being in its side walls,

and in such case the tip may be made of transparent material or may be omitted. Windows 12 may be provided with shutters which can be controlled from the proximal end of the intrascope which is outside of the examined part.

The illuminating system may consist of the electrical bulb 7. The electrical bulb may be mounted in the housing box 5 by means of a socket 7a. In some cases it is advantageous to use the objective lens 11 between the light bulb and window 12 in order to concentrate the light .on one field. The lens may be held in position by brackets 11a. The light bulb is activated by the source of electrical power. 9 situated outside of the examined part. Such a source may be the commercial electrical current or battery of dry cells. The flexible electrical cable 8 leads from the socket 7a to said outside source of electrical current '9. The cable is a lacquered, double insulated electric wire, is covered in addition with liquid rubber and is vulcanized in order to prevent a short circuit. The housing unit 5 may be in some cases omitted and the light source may be attached to the socket 7a which is held by brackets.

' In the flexible part 2a proximally' to the housing box 5, there is a rigid non-transparent housing compartment 14 containing the optical system 15 and the novel television pick-up tube 16a and 16b. The housing 14 has an opening 17 in which the optical system 15 is lodged and which serves to admit the image of the examined part. This opening is correlated with windows 18 in the flexible part of the intrascope which transmit the image of the examined part. In some cases the windows 18 may be made to extend over all the circumference of the intra scope. The windows 18 may be provided with shutters operated from the proximal end of the intrascope which The housing 14 containing the television pick-up tube 16a and 16b and the optical system may be attached to the inner wall of the flexible part 2a of the intrascope by means of brackets or may be held by springs. As the housing box fits into the encasing holding member 216 and is held by it tightly,

in some cases no additional supporting means such as springs are necessary.

The optical system 15 may consist of 90 gable prism 20 and of lens 21. The optical system may have its own housing unit instead of being lodged in the compartment 14 and may then be introduced into the intrascope separately.

In some cases it is desirable to have a large field of vision and at the same time to preserve the necessary magnification of the examined part. In such a case instead of the prism 20 a rotating mirror should be used. The mirror has first surface coating which eliminates the reflections and is activated by the magnetic solenoid placed beneath the mirror. The solenoid is connected by the elastic cable with the controls outside of the examined part and can tip the mirror from the retrograde position to the forward position giving thereby an additional field of vision without the necessity of moving the intrascope. The image of the examined part is reflected by the mirror on the objective lens which focuses said image on the photocathode of the novel television pick-up tube 16b described below. In case the magnification of the examined part is not necessary a large field of vision can be obtained by using the lens providing field of vision instead of the usual 45-50". The image produced by the optical system is inverted but it can be reverted to the original position either by an additional lens or electron-optically in the viewing tube. The rotating mirror may also serve to admit image either through window 18 or 18a without rotating the whole camera 16.

The housing box 14 contains the novel miniature television camera 16 which was designed to reduce to the minimum the size of the television camera. The television pick-up tubes known previously in the art could be miniaturized only to a certain degree, which was not sufficient in certain applications as some of the examined parts are too small to allow the introduction even of the smallest conventional pick-up tube. This is true especially for the type of tubes having external deflecting coils such as of magnetic or electro-magnetic type, and in such situations, my novel camera 16 will be very suitable as it does not require any external deflecting or focusing coils at all. The camera 16 consists of two vacuum tubes 16a and 16b. The tube 16a has an electron gun 28 which produces an electron beam '29. The electron beam 29 is focused by electrostatic field 30. The electron-optical system for focusing the electron beam 29 may be simplified and markedly reduced in length by using the unipotential electrostatic lens instead of the usual two-lens system. The electron beam 29 is deflected by electrostatic plates 30a and 30b in two perpendicular to each other planes. The electrostatic plates are energized by signals from saw-tooth generators 32 which are situated outside of the examined part. The generators 32 are connected with electrostatic plates 30a and 30b by means of flexible wires. One deflecting field is produced by the horizontal deflection plates 30a and may have line frequency such as 5-l5,000 cycles per second. Another deflecting field is provided by the vertical deflection plates 3% and may have field frequency such as 15-60 cycles per second. In this way the electron beam 29 is made to scan the fluorescent screen 31 in a regular television raster. The fluorescent screen 31. may be provided with electron transparent metallic conducting backing layer 31a such as of aluminum. The fluorescent screen 31 must be of a phosphor of a very short persistence in order to obtain a good resolution of the image. ZnO has decay time of 1 microsecond and is suitable for this purpose. Still better results may be obtained by means of ZnS phosphor and using only ultraviolet component of its fluorescent emission which has decay time of microsecond. In some cases, it is preferable to make the fluorescent screen 31 of semi-spherical curved shape as it will improve delinition of the flying light spot. The fluorescent layer 31 may also be deposited on a supporting mesh screen instead of being deposited on the wall of the vacuum tube. This will improve definition of the flying light spot.

The vacuum tube 16a operates in combination with the vacuum tube 16b forming together the novel television camera 16. The vacuum tube 16b has a photoemissive electrode 33 which may be deposited or attached to one of the walls of said vacuum tube. In some cases it is preferable to provide a light transparent conducting layer 33c such as of material known in the trade as Nesa, or of compounds of tin or of cadmium, on the side of said photoemissive electrode 33 facing the fluorescent screen 31. Such a layer must be very thin, e.g., of the order of microns in order not to impair the definition of images produced by the novel pick-up tube. The photoemissive electrode 33 may be of CsOAg or of caesium, lithium or rubidium on antimony, arsenic or bismuth. At the opposite end of the vacuum tube 16b there is provided photocathode 34 which consists of a light transparent signal plate 34a, a light transparent insulating layer 34b and of a photoemissive mosaic 340. The signal plate 34a may be a thin transparent layer of metal or other conducting material. The insulating layer 34b may be of mica, silica, or other transparent dielectric material and photoemissive mosaic 34c may be of CsOAg or of caesium, rubidium or lithium on antimony, arsenic or bismuth. In some cases the photoemissive layer 340 may be, instead of a mosaic, also of continuous type. In cases in which electrostatic focusing field 23 is used to focus the scanning electron beam 33a on the mosaic 34c, much better resolution will be obtained by making such mosaic of a curved semi-spherical shape. In addition, the use of such spherically shaped photocathode will eliminate instability of the image which is very marked when using electrostatic fields for focusing a slow electron beam.

The light image of the examined part is projected by the optical system on the photocathode 34 of the vacuum tube 16b. The light image produces emission of photoelectrons from the layer 34c. As a result, a positive charge image having the pattern of said light image is left on the photoemissive mosaic 340. Both vacuum tubes 16a and 161) are held in apposition to each other and in such a manner that the fluorescent screen 31 of the vacuum tube 16a is adjacent to the photoemissive electrode 33 of the tube 16b. The scanning electron beam 29 impinging on the fluorescent screen 31 produces a light spot at each point of its impingement. The scanning illumination excites the photoemissive electrode 33 and produces thereby a fine scanning beam of photoelectrons 33a. The photoelectron beam 33a is of the scanning type because it is produced by the scanning electron beam 29. The photoelectron beam 33a may be further focused by electrostatic fields 23. In this construction it is preferable to use focusing fields because the separation of the fluorescent screen 31 from the photoemissive electrode 33 by the thickness of the wall of the vacuum tubes 16a and 16b causes certain unsharpness of the photoelectron beam 33.

The electron beam 33a may be of high velocity such as used in the iconoscope type of television pick-up tubes or may be of a slow velocity. In this embodiment of my invention, I use the slow scanning electron beam. It is to be understood, however, that the fast scanning electron beam may be used in my invention as well. The electron beam 33a scanning across the charge image stored in the mosaic 34c converts said image into elec trical signals which appear at the signal plate 34a. These electrical signals can be converted into video signals over the resistance in the manner well known in the art. The video signals are transmitted by the flexible coaxial cable 43 from the intrascope within the examined part to the video amplifiers 4311 outside of said part. The amplified signals are transmitted from the amplifiers to the viewing tube of kinescope type 37 and are reconstructed therein into the visible image representing the image of the examined part. The viewing tube may be of kinescope type and does not have to be described in detail as it is well known in the art. The examined part will appear on the fluorescent screen 37a of the viewing tube where it can be inspected by many examiners. Transmission of the image from the amplifier 43a to the viewing tube can be done by coaxial cable 43 or by high frequency waves. The image can be sent therefore not only to the immediate but also to. the remote receivers or may be transmitted to multiple independent viewing tubes for the benefit of many examiners, which was one of the objectives of this invention. The image on the viewing tube 37 may also be photographed simultaneously with the intrascopic examination in orderto make a permanent record, which was another purpose of this invention.

The contrast of the reproduced image may be changed, diminished or increased according to the needs of particular examination by using amplifiers provided with variable mu tubes, or by the use of kinescope in which gamma can be controlled. The signal to noise ratio of this system and therefore the definition of the reproduced image may be improved by using in amplifiers discriminating circuits which reject signals below the predetermined amplitude and eliminate therefore most of the noise signals. The coaxial cable 43 within the examined part may be encased in the above-described means 26 or 26a for inserting intrascope or may be attached to them.

The voltages for the operation of the tubes 16a and 161) are supplied through the flexible elastical wires 8a from the source of the electrical power 9 outside of the examined part. In the same way the horizontal and vertical synchronizing circuits, focusing fields and deflecting circuits are supplied with electrical energy from the outside source of power 9. The synchronizing and deflecting circuits and focusing fields are not described in detail as they are well known in the art and it is believed they would only complicate the drawings. In some cases the coaxial cable may be outside of said inserting means 26 or 26a. I

The housing 14 containing the television camera can be rotated in its position in the intrascope, so that the optical system 15 can be made to face the window 18 or 18a and to see thereby various areas of the circumference of the examined part. The rotation of the camera can be accomplished by means of a pusher 15a which fits into extensions 1% of the box 14. The rotation of the camera may be preferable in some cases to the rotation of the whole intrascope which allows to accomplish the same purpose.

The main rigid portion of the flexible intrascope is the television camera 16. Therefore the shorter the tele vision camera is, the easier it will be for the intrascope to pass through sharply angulated or curved passages. One of the advantages of the novel pick-up tube 16 is that it makes it possible to break up the smallest pick-up tube into two component parts such as tubes 16a and 16b and introduce each of said tubes into the examined part separately, reducing thereby considerably the rigid portion of the intrascope which is due to the television camera, as shown in Fig. In.

To accomplish these objectives the flexible intrascope 1a is introduced first into the examined part while containing only the box 5 housing the light source 7. Inside of the intrascope 1a, proximally to the box 5 there is a ring-like partition which serves as a stop 27 for the pickup tube 16b which is to be introduced later. It is obvious that the shape of this stop may vary. The rest of the intrascope 1a is empty. The intrascope 1ais introduced first into the examined part. As the only rigid part in the intrascope is now the box 5 which is very small, this intrascope can easily pass even through very narrow and 7 curved passages. Afiter the intrascope 1a has been introduced into the examined part for a desired distance which can be read easily on the markings provided on the outside wall of the intrascope, the next step begins. Now the housing box 14b in which the vacuum pick-up tube 16b is mounted is introduced into the intrascope. The housing box 14b is pushed into the intrascope until it reaches the stop 27, which can be also ascertained by the X-ray control. The box 14b may be held against the stop 27 by spring extensions 27a on said stop 27. The housing box 14b may be pushed into its position by a flexible elastic guide 15a which is fitted into the proximal end of the housing box 14b. For this purpose the housing box 14b is provided with a ring-like extension a at its base as shown in Fig. 1a, which has spring-like properties. The head of the flexible pusher a fits into this extension and is kept in position by it. The flexible pusher 15a may also be provided with electrical coils 6a at its distal end which is adjacent to the element to be introduced into the intrascope. The coils 6a are connected to the source of electrical power situated outside of the examined part. In this way, the head of the pusher may be given electromagnetic properties by closing the circuit, energizing said coils 6a. The pusher 15a will be held therefore in the elements to be introduced into the intrascope, such as boxes 14a, 14b or the optical system 15, not only by the mechanical pressure of the extensions 10:: or 16b but by magnetic attraction as well. When the pusher 15a is to be withdrawn, the current supplying the coils 6a is shut off. To facilitate the guiding of the box 14b into the intrascope, a set of threads 86 may be used which are at one end attached to the stop 27, and which are threaded through the perforations in the extensions 87 of the housing box 1412. After the box 14b has been introduced into its proper position in the intrascope, the pusher 15a, is removed. Another set of threads 89 is attached to the extensions 88 in the housing unit 1412 and serves to pull out said box 14b to the exterior of the examined part when the examination is finished. This arrangement is shown in Fig. 1b.

The housing box may be omitted in some cases and the tube 16b may be introduced into the intrascope without any housing and will be held in position by the same means as described above for holding the box 14b.

After the box 1412 with the tube 16b has been introduced, the box 14a housing the tube 16a is introduced now into the intrascope in a similar manner as was described above. Both boxes 14b and 14a have openings at their proximal and distal ends respectively, which makes it possible to bring the fluorescent screen 31 of the tube 16a in close apposition to the photoemissive electrode 33 in the tube 16b. The boxes 14a and 14b are provided with mechanical means for securing a good contact of the proximal end of the tube 16b with the distal end of the tube 1601. One way of providing such a contact is to make the compartment 14a fit inside of the spring-like flange 27a at the proximal end of the compartment 14b. The housing box contains vacuum tube 16a which has been described above. The housing box 14a is provided with spring-like extensions 19b, which serve to accommodate the head of the pushing guide 15a.

The housing box 14:: is pushed into the intrascope until it reaches the position of the stop 27b. This can be also checked by the X-ray control. The stop 27b is so situated that when the housing box 14a reaches it the tubes 16b and 16a will be in apposition to each other. In some cases flexible coils which can be converted into magnets by passing through them an alternating current from an outside source of electrical power may be provided on the stops 27 and 2712 or at extensions 10a or 1012 of the intrascope to help the'positioning of boxes 14a and 141). In this way the rigid portion of the intrascope which has to pass through a narrow passage or acute curvature is now only a fraction of. the rigid part of intrascopes which use even the smallest pick-up tube of conventional type. This represents an important improvement as it makes it possible'to introduce the intrascope into parts which were not accessible previously to examination. In case the size of the pick-up tube is not of critical importance, one of standard television tubes after being miniaturized may be used as well.

The size of the kinescope tube 16a may be reduced considerably if it can be operated at a low voltage and produce at said low voltage suflicient illumination of the electrode 33. One way of accomplishing this purpose is disclosed in my U. S. Patent No. 2,586,391 which discloses an amplifying screen consisting of a light reflecting layer, a fluorescent layer, a light transparent separating layer and a photoemissive layer. Said screen is disposed in the kinescope between the electron gun and the fluorescent image reproducing screen. The same objective may be also obtained by using between the electron gun and the image reproducing screen a secondary electron emissive electrode which may be of a solid type or preferably of mesh screen is of material having a high secondary electron emission ratio such as AgzMg or it may have deposited on a mesh screen a layer of a highly electron emissive material such as of CS0 or of CsSb. As 6-10 electrons may be emitted by said screen for each incident electron, the voltage of the kinescope may be considerably reduced. The electronoptical field between said secondary electron emissive electrode and the fluorescent screen 31 will focus the divergent secondary electrons into fine beams sothat the definition of the image will not be markedly impaired.

There are certain drawbacks in the intrascope 1 or 1a described above. The separation of the fluorescent screen 31 from the photoemissive electrode 33 by the thickness of the wall of the vacuum tube 16a and of the tube 16b causes some unsharpness of the photoelect-ron beam 3311. This unsharpness is due to diffusion of a light spot from fluorescent screen 31 as it travels through distance equal to the thickness ofthc walls of the tubes 16a and 1611. By the time the light spot reaches the photoemissive electrode 33 it has spread so that it cannot produce any more a fine photoelectron beam. Besides the fluorescent light spot suffers in the glass Walls of the tubes 1 6a and 16b multiple internal reflections so that part of the fluorescent light will be scattered and will strike difier- 'ent separated areas of the electrode 33 reducing thereby further definition and contrast. Furthermore, it is not always possible to introduce component parts of intrascope separately as was described before. In some examinations, the time available is very limited so that intrasco-pe must be ready for the use as soon as possible. In such cases, another modification of my invention is more suitable. This embodiment 1b of the intrascope is shown in Fig. 2. In this embodiment of invention the tubes 16a and 1612 are replaced by one vacuum tube having a composite target 19 described below. The fluorescent layer 31b of phosphors described above is deposited on one side of a very thin light transparent separating partition 1% whereas the photoemissive layer 33b of one of the materials described above is deposited on the opposite side of said partition. The partition 19a may be of mica, glass, or of a suitable plastic and should be preferably very thin such as of the order of a fraction of a millimeter in order not to impair definition of images produced by the said television pick-up tube. Better results may be obtained if the partition 1% is conductive. This may be accomplished by using for the partition a conductive material or by coating the partition on the side which supports the photoemissive layer with a light transparent conducting layer such as is known in the trade under the name of Nesa, indium compounds, or with light transparent conducting layer of tin compounds or of cadmium compounds. In some cases the composite target 19 may be deposited on the photocathode 9 '34 instead of being supported by the side walls of said pick-up tube. In this event the separating layer 19a may be preferably reduced to the thickness of a fraction of one micron.

The partition 190 may be placed in its position within the tube 160 by means of a metallic ring 98 having a flange 99 which supports the partition, whereas the ring itself is attached to the walls of the tube. The crosssectional perspective view of the ring 98 and partition 19a is shown in Figs. 2d and 2e. Instead of a metallic ring 98, the transparent separating layer 19a, the fluorescent layer 31b and photoemissive layer 33b may also be supported by the mesh screen of conducting or insulating material 82 as shown in the pick-up tubes 16d and 26e and 16e' illustrated in Figs. 2a, 2b and 2c. Instead of a mesh screen a supporting layer of continuous type may be used and may be made of one of the materials used for the separating layer 19a which are either light transparent or electron transparent. In some cases it is preferable to make the fluorescent layer 31b and the photoemissive layer 33b of semi-spherical curved shape. In some cases, the separating partition 19a may be omitted and the fluorescent layer 31b and photoemissive electrode 33b are both supported by the mesh screen 82 or by supporting element of continuous type 19a without any separating layer. This arrangement is possible only in cases in which the photoemissive layer 331; and fluorescent layer 31b do not inactivate each other and the photoemissive layer 33b is conductive. The other elements of the novel pick-up tubes 16c, 16d and 16a are the same as described above. At one end of the tube 160 there is disposed an electron gun 28 which produces an electron beam 29. The electron beam 29 is focused by electrostatic field 30 and is deflected by electrostatic plates 30a and 30b in two perpendicular to each other planes. The electrostatic plates are energized by signals from saw-tooth generators 32 which are situated outside of the examined part. The generators 32 are connected with electrostatic plates 30a and 3012 by means of flexible wires. In this way, the electron beam 29 is made to scan the fluorescent layer 31a of the composite target 19 in a regular television raster. The fluorescent layer 31b may also be provided with an electron transparent metallic conducting backing layer 31a such as of aluminum. The fluorescent scanning light spot produces a scanning photoelectron beam from the photoemissive electrode 33b which may be of CsOAg or of caesium, lithium or rubidium on antimony, arsenic or bismuth. At the opposite end of the vacu-v um tube 160 there is provided photocathode34 which consists of a light transparent signal plate 34a, a light transparent insulating layer 34b and of a photoemissive mosaic 340. The signal plate 34a may be a thin trans: parent layer of metal or other conducting material. The insulating layer 34b may be of mica or other transparent dielectric material and photoemissive mosaic 34c may be of CsOAg or of caesium, rubidium or lithium on antimony, arsenic or bismuth, as was described above.

In some cases it is preferable to focus the scanning electron beam 33a on the photocathode 34. The focusing has to be done by means of electrostatic fields 30a. In such event the photocathode 34 or its photoemissive mosaic 34c preferably should be of curved semi-spherical shape. The rest of the operation of the intrascope 112 using the television camera 16c is the same as was described above. A considerable improvement in definition of reproduced images may be achieved by making the fluorescent screen 31 of grainless phosphors.

The housing box may be omitted in some cases and the television tube may be introduced into the intrascope without any housing and will be held then in position by the same means as were described above for holding the housing box.

"In some cases the part to be examined is too small or too'curved to accommodate even the television camera 16. For example the introduction of the intrascope 1a through narrow passages may be in some cases accomplished because of separate two-step insertion of the tubes 16a and 16b, but their subsequent assembling together inside of the intrascope proves to be impossible because of the lack of sufiicient space. In such cases, it may be necessary to keep the tubes 16a and 16b apart from each other and to use an optical system 150 to focus the scanning illumination produced by the tube 1611 on the photoemissive electrode 33 in the tube 16b, as shown in intrascope 10, illustrated in Fig. 3.

In some cases the optical system 150 may be housed in the compartment 14b. In other cases it may be placed preferably in compartment 14a. It must be added that the use of the optical system 15c makes it necessary to increase the output of light from the fluorescent screen 31, as only 2% of the light will now reach the photoemissive electrode 33. The rest of the operation of the intrascope 1c is the same as was described above for the intrascope 1 or 1a.

This arrangement will be useful in locations which are known in advance as not to cause any bending of the intrascope in the area between said tubes 16a and 1611. It may be also of value in the examination of parts where the degree of such angulation between the tubes 16a and-16b is known in advance so that it may be overcome by the choice of a suitable optical system.

In order to reduce pin-cushion distortion inherent in electrostatic deflection system used in cameras described above-and illustrated in Figs. 1 to'3, I make the fluorescent screen of a'semi-spherical shape. Furthermore, the photoemissive electrode 33 may be preferably also shaped semi-spherically to reduce further pin-cushion eflects. In addition, the photocathode 34 of the pickup tube may also preferably have a curved semi-spherical shape which will help to overcome further distortion due to electrostatic focusing field 30a. The use in combination of a curved fluorescent screen 31 and of a curved photocathode 34 represents an important improvement of my camera over devices of the prior art. The definition of the flying light spot may be considerably improved by depositing screen 31 on a supporting mesh screen 83 which was described above, instead of on the wall of the tube 16.

In case extremely bright images have to be investigated the photocathode 34 of the pick-up tubes described above may be provided with a layer of phosphor on the side facing said image, which converts the radiation of strong intensity into a fluorescence or phosphorescence of weak intensity, so that the pick-up tube will not be damaged by excessive illumination. Such phosphors are well known in the art. Therefore it is believed that their description is not necessary.

In some cases it is preferable to reduce further the rigid part of the intrascope by providing the source of image forming radiation outside of the intrascope. This embodiment of my invention is shown in Fig. 5.

The photocathode of the pick-up tube 161.5 may be also made to provide a panoramic view of the examined part. The photocathode 34' in this modification is extending in a curved semi-spherical manner to the side walls of the pick-up tube, as shown in Fig. 5. One window 12a in this modification is preferably situated at the end of the intrascope.

The novel intrascope 1 or 1a may be further simplified as shown in Fig. 4. In this embodiment of my invention only one novel pick-up tube 167 is used. The pick-up tube 16 has a photoemissive photocathode 34g which consists of a layer 34a transparent to image form! ing radiation, a dielectric layer 34b also transparent to the image forming radiation, and photoemissive mosaic 34c. In a close spacing from the photocathode 34g, such as. not exceeding 0.25 millimeter but preferably much smaller, there is disposed a fluorescent screen 34e.-

11 The screen 34a may be supported by a light transparent supporting layer such as of mica or may be supported by a mesh screen 32 as was described above. The fluorescent screen 34:: may be in some cases provided with an electron transparent light reflecting conducting layer 341 on the side facing the electron gun 28. In some cases,

said fluorescent layer 3442 and backing layer 34 may be deposited on the photoemissive mosaic 340, as shown in Fig. 4. In such event, a light transparent separating layer 34d may be preferably interposed between said photoernissive and fluorescent layers. At the other end of the tube there is disposed an electron gun 28 which produces an electron beam 2? for scanning said fluorescent layer 34g in television raster. The image of the examined part is projected on said composite photocathode 34g and produces a charge image in the photoemissive mosaic 340, which has the pattern of said projected image. The scanning electron beam produces scanning light spot in the fluorescent layer 34b. The light spot scans the adjacent photoemissive layer 340. The impingement of the light spot causes photoemission of electrons which is modulated by the charge image established in the mosaic 340 by the projected previously image of the examined part. The signals produced by the scanning light spot appear at the signal plate Sea and can be converted over suitable resistor into video signals in the manner well known in the television art. The light transparent separating layer 3411 is necessary to prevent detrimental chemical interaction between the photoemissive layer 340 and fluorescent layer Me. In order to preserve sharpness of the scanning light spot said separating layer must not exceed 0.15 millimeter in thickness. The layer 34d may be dielectric such as of mica, non-conductive glass or plastics. In some cases it is preferable to use a conductive layer and in such event the separating layer may be of glass, mica, plastics coated with the material known as Nesa manufactured by Pittsburgh Plate Glass Company. It may be also made of tin salts such as halides or oxides, cadmium salts or metal powders such as of silver. In some cases it is preferable to make the separating layer of two layers adjacent to each other, one of them being an insulating or semi-conducting layer, another one being a conducting layer. It is obvious that the composite photocathode 34g may be deposited on the wall of the vacuum tube or may be held by supporting means within the vacuum tube independently of the end walls of said tube. Such supporting means may be either in the form of mesh screen or of a continuous element which both were described above. The fluorescent layer 4e must be of phosphors having a very short persistence such as'of the order of l microsecond, which were described above. The electron transparent layer 34; serves to improve efliciency of the light output from the fluorescent layer 34c and may beof aluminum. In some cases it may be omitted.

This system may be used also in the way shown in the intrascope 1a which has optical system between pickup tube 16b and tube 16a and it is shown in Fig. 4a. In such a case the novel pick-up tube 161) has the mosaic photocathode 34 described above but the electrode 33 is eliminated, see Fig. 4a. The scanning of charge image produced on the photoemissive mosaic 34c is accomplished by the fluorescent light spot from the tube 1611 which is projected on the mosaic Me by lens c. The impingement of the flying light spot which scans the photocatnode 34 in television raster produces photoemission from the layer 340 which is modulated by charge image present thereon. As a result successive electrical signals are formed which can be taken oh the signal plate 34a and can be converted into video signals in the manner well known in the art.

This novel television camera can also be used by placing the novel tube 16b in close apposition to the tube 16a; see Fig. 4b.

The fluorescent screen Me if made of a curved semispherical shape will help to reduce pin-cushion distortion inherent in electrostatic deflection systems. In addition the photocathode of the pick-up tube 16b may also preferably'have a curved semi-spherical shape which will help to overcome further distortion due to electrostatic scanning. The use in' combination of a curved fluorescent screen and of a curved photocathode represents an important improvement of my camera.

The intrascopes illustrated in Figs. 4, 4a and 412 may also be simplified by providing the source of image forming radiation outside of the intrascope as was explained above.

In case a true color image of the examined part is Wanted, a rotating color wheel 50, drum, or truncated cone, composed of plural, e.g., three primary chromatic filters 51, 52 and S3, is placed before the television pickup tube 16b; see Fig. 6. A similar wheel 50a rotating synchronously with the first color wheel 50 is placed in front of the picture tube 37 in the receiver. Each examined field is scanned and reproduced in succession through a different primary color in the filter wheel. Therefore three colored red, green and blue are projected on the final viewing screen 56 in 4 second. The persistence of vision lasts longer than of a second. Therefore these three color images fuse in the mind of the observer and a multi-colored reproduction 57 corresponding to the true colors of the examined part results. The color wheels 50 and 50a are driven by induction motor located outside of the examined part, synchronized by synchronization stage which compares the incoming pulses with locally generated ones and thereby contols the speed and the phase of the disc. Since the color wheels synchronization is obtained from the video wave form, the phasing of the color filters is automatically selected, that is a given color automatically appears before the receiver tube when that color is present before the pick-up tube, as it is well known in television art.

The illuminating system 5 in this modification of the intrascope is the same as described above and shown in Fig. l. The mounting of the illuminating system also may be the same as shown in Fig. 1. The optical system 15 is essentially the same as described above and shown in Fig. 1. In some cases additional lenses may be used between the rotating wheel 50 and the television pick-up tube 16b, 16 or any other pick-up tubc described above for a better focusing of the image of the examined part on the photocathode of the pick-up tube. The mounting of the optical system may be the same as shown in Fig. 1. The rotating color wheel 50 in front of the television pick-up tube has three sections of colored glass correspending to three basic chromatic values such as red 51,

blue 5-2 and green 53, and may be mounted on the bracket 59. The rotating wheel is activated by the synchronous motor situated outside of the examined part and connected to the wheel by means of the flexible insulated cable.

The image of the examined part is projected by the optical system onto the photocathode of the television pick-up tube through the rotating multicolor wheel 50 and is converted by said television pick-up tube into video signals having the pattern of the examined part in the same way as was explained above. The video signals are transmitted by the flexible coaxial cable to the amplifiers outside of the examined part. The amplified video signals are conducted by the coaxial cable to the viewing tube 37 of the kinescope type. The video signals modulate the scanning beam 60 of the kinescope 37. The modulated scanning beam in the kinescope striking the fluorescent screen 61 of the kinescope is reproducing the images of the examined part. These images are projected through the color wheel 50a rotating synchronously with the similar color wheel 50 in front of the pick-up tube. in this way three colored images of the examined part are projected on the final screen 56 in A of a second, blending thereby into one 13 multicolored image due to persistence of the vision of the observer. The resulting multicolored images 57 can be visually examined on the screen 56 or may be recorded. It is obvious that with all intrascopes described above this color system may be used.

In some cases the use of therotating color disc, drum or truncated cone may not be convenient, and a system using a stationary color filter may be preferable. 'It is obvious that the rotating color disc may be replaced by stationary color filters such as dichroic mirrors, but in such case two or three pick-up tubes must be provided in the intrascope. It is to be understood that all such color television systems come also within the scope of my invention. In order to use a stationary color filter with one pick-up tube only it is necessary to split the image by suitable optical means into plural, e.g., two or three images and to project said split images through the stationary color filter on separate areas of the photocathode. This embodiment of my invention is shown in Fig. 7. The image 64 of the examined part is projected by lens 65 between two mirrors 66 and 67. The mirrors are parallel to each other and equidistant from the optical axis. The mirrors produce from the original image 64 multiple secondary images such as 64a, 64b, 640, etc. The lens 65a projects the image 64 and the secondary images 64a and 64b on the different areas A, B and C of the photocathode 68 of the pick-up tube, which may be of any type described above. There are many optical systems for splitting the image of the examined part into plural symmetrical images, which are well known in the art; see US. Patents Nos. 2,389,646 and 2,465,652, and it is to be understood that thedescription of the optical system used in my intrascope should be considered only in an illustrative and not in a limiting way.

Each photocathode 68 has signal plate 69, dielectric layer 70 and photoemissive mosaic layer 71, as was de scribed above. Three symmetrical images are projected on diiferent areas A, B and C of the photocathode without overlapping each other. The stationary color filter having plural elements such as the red one 67, the green one 67a and the blue one 67b, are provided either outside of the pick-up tube in cooperative relation with said three difierent areas A, B and C of the photocathode for receiving the original image 64 and symmetrical images 64:: and 64b. The filters may also be positioned inside of the pickup tube in front of the photocathode. Therefore the image 64a which passes through the red filter 67 will produce in the area A image 64a having red information. The image 64 which passes through the green filter 67a will produce in the area B image 64' providing green information, and the image 64b produced by the filter 67b will form in area C image 61b which provides blue information. The scanning electron beam 33a produced by the flying spot light as explained above, scans these images on the photocathode and produces video signals having the pattern of said red, green and blue images. When the area A of the photocathode is scanned video signals are produced which after amplification and improvement of their contrast are fed into red kinescope. Next the electron beam 33a scans the area B and image 64' and converts said image into video signals. These video signals correspond to the green image 64' and are fed into green kinescope. In the same way the video signals corresponding to the blue image 64b are fed into the blue kinescope. It is obvious that instead 'of multiple kinescopes a single tricolor kinescope may be used as well. It is also evident that the scanning of the charge images on the photocathode does not have to proceed systematically from the area A to area B but also may be completely interlaced. The basic feature of all these arrangements is that video signals derived from the scanning of the area A of the photocathode have to be fed into red channel, the signals produced by scanning area B of the photocathode have to be fed into green channel and signals from area C should be fed into "blue channel.

It is obvious that there are many systems which can produce plural non-overlapping images and it is to be understood that all such systems come within the scope of this invention. It is also obvious that optical means or filters may be used to split not the whole image simultaneously into plural symmetrical images but to split'eaoh line of the image into three non-overlapping line images. These line images may be projected through multicolor filter to produce non-overlapping color line images. Each of said lines will then be scanned and converted into red, blue and green video signals as was explained above.

The television camera of the type shown in Figs. 4, 4a and 4b can also be used in this novel color television intrascope. Fig. 7a shows the use of the pick-up tube 16g for producing color images. It is obvious that the same system may be used with pick-up tubes 16b or 16b The novel pick-up tube 16g has a mosaic photocathode 76 which consists of a light transparent conducting layer 76a, light transparent dielectric layer 76b and of photoemissive mosaic layer 760. The above mentioned layers may be of the materials described above. The photocathode 76 may be divided into plural areas such as three independent from each other photocathodes, as was shown in Fig. 7. This may be accomplished also by the insulating means which extend from the conducting layer 76a into photoemissive layer 760. In another modification instead of this plural photocathode, three independent photocathodes may be deposited on the walls of the pick-up tube or may be mounted in the inside of said pick-up tube in such a manner that the edges of said photocathodes do not come in contact with each other. In the preferred form of this system, the optical projection of split images is of such a manner that said images do not overlap each other on the photocathode but fall in three separate areas A, B and C. In such case, only the signal plate 76a has to be-divided into three different areas such as 76A, 76B and 76C which are insulated from each other or are non-contiguous to each other. In order to be able to transmit red video signals only to the red channel, green video signals only to the green channel and blue video signals only to the blue channel in this modification the photoemissive mosaic 76c and its dielectric layer 76b do not have to be split any more into independent non-contiguous units. By the use of one of the optical systems described above, the image of the examined part is split into three separate images which are projected on three separate areas 76A, 76B and 76C. Each of the conducting signal plates of said photocathodes is connected to its own color channel only. In this way the signals from the signal plate 76A will be, for example, directed to the red kinescope, the signals from the signal plate 76B to the green kinescope and signals from the signal plate 7 6C will be fed into the blue kinescope.

Another way to produce color images is to subject various areas A, B and C of the photocathode or the scanning beam to modulation by signals of different frequencies from an outside generator and by making each primary color channel responsive only to one frequency which is made arbitrarily representative of said primary color. In this way the red, green and blue images will be fed into red, green and blue channels respectively by means of appropriate filters or decoders. This arrangement allows the use of one signal plate instead of three signal plates in the systems described above.

My invention is not limited to 'visible light images. It is evident that my intrascope may be made responsive to invisible images on either side of visible spectrum by using appropriate photosensitive layer in the photocathode of the television camera. It is to be understood also not only by various electromagnetic radiations, such as ultra-violet, infra-red, etc., but also by particles radiation such as neutrons, alpha particles, protons, electrons or by ions. In such case, the photocathode of the pick-up tube described above may be provided with an atomic particle sensitive phosphor on the side facing said image or may have a special electron or other atomic particles emissive photocathode. Such photocathodes have been described in my US. Patents Nos. 2,525,832, 2,555,423 and 2,603,757.

Fig. 8 shows a pick-up tube 1611 having atomic particles sensitive photocathode which is responsive to an atomic particles image and emits secondary atomic particles having the pattern of said image. It is to be understood that the photocathode 77 is shown only for illus- I tration as there are many types of pho-tocathodes sensitive to atomic particles, as evidenced by my above mentioned patents. The target 78 is scanned by a slow electron beam 33a from the electrode 38 in the manner described above. The electrons of the scanning beam 33a are deposited on the dielectric layer 79 of the target and are stored there. At the time of impingement of the beam of gamma rays or of atomic particles from the photocathode 77, the dielectric layer 79 becomes conductive. The electrons of the scanning beam 33a can now pass through the dielectric layer 79 to the signal plate '80 and produce video signals. In some cases the photocathode 77 may be in apposition with the target 78.

The above described type of pick-up tube may also operate using a fast scanning electron beam instead of a slow beam. This modification is preferable in cases in which the particles emitted by the photocathode 77 have small velocity, for example, in case of a photoemissive cathode. In such case the signal plate 80 should be on the side of the target '79 which faces the scanning electrode 33. The rest of the operation of this intrascope may be the same as described above.

The storage target may also be of the composite type and may consist of a fluorescent light reflecting layer 81, a fluorescent layer 81a, a light transparent dielectric layer 81b, such as of mica, glass or silica, and a photoemissive mosaic layer 81a, as shown in Fig. 8a. In some cases the photocathode 77 and the composite storage target 83 may be in apposition to each other, which means contiguous to each other. In some applications the storage target 83 may also be used instead of the photocathode 77 and will serve to receive an image of invisible radiation and to convert said image into a charge image. Also the target 78 may serve as a photocathode; see Fig. 812.

Furthermore, my intrascope may serve for investigating images produced by supersonic radiation. In such case, the photocathode of the pick-up tubes described above is replaced by the supersonic sensitive photocathode, for example, of the type described in my co-pending applications, Serial Nos. 288,229 and 286,521 filed May 16, 1952, and May 7, 1952, respectively. The intrascope must have at its distal end a membrane and must also have a medium to transmit supersonic vibrations to pick-up tube. Instead of a membrane, the end-wall of pick-up tube may form the end of intrascope and will then receive supersonic image directly.

When using an invisible radiation for producing an image of the examined part, the color reproduction of said image may also be obtained, as it is explained in my US. Patent No. 2,593,925. Another system for color reproduction of invisible radiation images is to make separate sub-photocathodes A, B, and C as described above, selectively sensitive to different groups of frequencies present in said invisible radiation image. For example, sub-photocathode A may be made to receive radiations only of wave-length 34000 A. either by means of a special selective filter in front of said subphotocathode or by making the photosensitive surface Figs. 5 and 8.

, 16 selectively responsive only to said wave-length. In the same manner the sub-photocathode B will receive only radiations of 1000-2000 A. It is obvious that the wavelengths quoted above should be considered only in an illustrative and not in a limiting sense.

.lective for various frequencies present in the invisible image may be used for the same purpose. This modification will then allow the useof only one photocathode instead of three sub-photocathodes.

1 In many cases it is preferable to have the source of invisible light or of other image forming radiation used for examination independent of my intrascope and outside of the intrascope. In such arrangement the source of image forming radiation may be introduced prior to or subsequent to introduction of the intrascope into the examined part. This embodiment of my invention will facilitate the insertion of the intrascope as it will reduce the size of its rigid parts.

The novel television cameras described above both .for invisible and visible image forming radiation operate by means of the photoemissive effect or by means of bombardment induced conductivity effect. It should be understood however. that similar television cameras which may use a photoconductive or photovoltaic effect instead of a photoemissive efi'ect come also within the scope of my invention.

It is evident that all intrascopes used for receiving images or signals of ionizing radiations such as gamma rays, electrons, neutrons, protons, etc. may'serve to reproduce images without having any optical system. In such case the window of the intrascope is preferably situated at the distal end of the intrascope as shown in All the intrascopes described above may be further reduced in size by omitting the encasing and holding member 26, as shown in Fig. 5a. In this modification of my invention, the television pick-up tube may be of any of the types described above. The television pickup tube may be inserted into the examined part by means of a flexible or semi-flexible pushing guide 15a, according to the type of the examined object. The television camera, e.g. 16e is placed in a housing compartment 92 which is provided at its proximal end with extensions 94 for receiving the head of the guide 15a. At the other end of the housing compartment an extension is provided for the optical system 93. In some cases a semi-flexible transparent tip or a tip having Window 91 therein may be provided at the end of the housing 92. In some cases additional windows with lenses may preferably be added in the side walls of the housing box 92. In such event the photocathode of the pick-up tube 16e should preferably be of a panoramic type, as was shown in Fig. 5.

The intrascopes of the type described above may be further simplified by omitting the housing box 92 and introducing television pick-up tube into the examined part without any protective compartment. In such case an extension or a socket is provided at the proximal end of the television camera to accommodate the head of the guide 15a. Another extension is provided at the distal end of the television pick-up tube to support the optical system 93.

In this modification of my intrascope the head of the pushing guide 15a may be fitted into extension at the proximal end of the camera tube in the same manner as was described above for fitting the guide 15a into extensions in the housing compartment. The pushing guide may also be screwed onto the socket mounted at the proximal end of the pick-up tube. Also electro-magnetic coils described above may preferably be used in this modification of my invention to secure a good contact.

In some applications it may be desirable to remove the guide 15a from the camera tube after its insertion. In such case the camera is provided with the threads 89 described above to pull out said tube after examination is concluded.

In some applications the pick-up tube may be encased in an inflatable transparent sheath which is inflated after the insertion of intrascope.

It is obvious that all these simplified intrascopes described above may also be used for producing color images of the examined part in the manner described above. It is also to be understood that these simplified intrascopes may be used in combination with a source of an invisible radiation either of corpuscular or of undulant type. Furthermore it is to be understood that the simplified intrascope may use pick-up devices based on the photoconductive or photovoltaic effect instead of the photoemissive elfect described above.

For producing color images in some cases instead of separate signal plates, a circuit having keying amplifiers may be used as well. This circuit activates amplifiers for video signals in a predetermined time sequence, so that the signals coming from the area A and representing red signals are amplified by amplifiers, whereas signals from the green area B and blue area C are not amplified and therefore are not reproduced. Next when'the green area B is scanned, the amplifiers receiving green signals are activated by said keying circuits, whereas amplifiers for red and blue signals are kept inactive. The keying amplifiers are well known in the art. It is believed, therefore, that their detailed description would only serve to complicate the drawings. In some cases, equalizing circuits should be provided in addition, in order to equalize diiferences in signals caused by different exposure time of the area A, B, and C to the image forming radiation.

It is to be understood that all systems described above for producing color images may be used in combination with all pick-up devices described above for producing black and white images.

My device may be also used, instead of reproducing images, for transmitting signals from the interior of the examined part, which signals represent desired information.

It will thus be seen that there is provided a device in which the several objects of this invention are achieved and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiment above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

What I claim is:

l. A device for exploring a passage comprising in combination a housing having a flexible portion, image sensitive means for receiving ionizing radiation from the explored part and converting said radiation into an electrical pattern, said image sensitive means comprising a luminescent layer and a photoelectric layer, means for producing a scanning illumination, means for directing said scanning illumination to said image sensitive means, said device furthermore comprising means for converting said electrical pattern into electrical signals corresponding to said pattern and means for transmitting said signals to the outside of said explored part.

2. A device as defined in claim 1 which comprises in addition means for producing color images.

3. A device for exploring a passage comprising in combination a housing having a flexible portion, image sensitive means for receiving ionizing radiation from the explored part and converting said radiation into an elec trical pattern, said image sensitive means comprising a layer of material exhibiting electrical conductivity changes when irradiated by said ionizing radiation, means for producing a scanning illumination, means for directing said scanning illumination to said image sensitive means, said device furthermore comprising means for converting said electrical pattern into electrical signals corresponding to said pattern and means for transmitting said signals to the outside of said explored part.

4. A device as defined in claim 3 which comprises in addition means for producing color images.

5. A device as defined in claim 1 in which said image sensitive means comprise a vacuum tube provided with electrostatic deflecting means for electron beam.

6. A device as defined in claim 3 in which said image sensitive means comprise a vacuum tube provided with I electrostatic deflecting means for electron beam.

7. A device for exploring a passage comprising in combination a housing having a flexible portion, image sensitive means having a photoelectric layer for receiving radiation from the explored part and converting said radiation into an electrical pattern, means for producing a scanning illumination, means for directing said scanning illumination to said photoelectric layer in said image sensitive means to scan with said illumination said electrical pattern, said device furthermore comprising means for converting said electrical pattern into electrical signals corresponding to said pattern and means for transmitting said signals to the outside of said explored part.

8. A device as defined in claim 7, which comprises in addition means for producing color images.

References Cited in the file of this patent UNITED STATES PATENTS 2,764,148 Sheldon Sept. 25, 1956 2,764,149 Sheldon Sept. 25, 1956 2,788,390 Sheldon Apr. 9, 1957 

